CN106761982A - A kind of new part backheating gas turbine combined cycle system - Google Patents

Abstract

The invention discloses a novel partial recuperation gas turbine combined cycle system belonging to the field of power station energy conservation. The system is mainly composed of gas turbine, combustion chamber, compressor, waste heat boiler, steam turbine, regenerator and other parts. In the simple regenerative gas turbine combined cycle system, the gas turbine exhaust gas is used to preheat the compressed air before entering the combustion chamber to increase the temperature of the air entering the combustion chamber, and the reheated flue gas is all passed into the waste heat boiler . In the present invention, only part of the exhaust gas of the gas turbine is used for heat recovery, and the proportion of flue gas involved in heat recovery is used to adjust the load when the load is relatively high, so as not to lose more work of the combined cycle of the gas turbine In the case of the partial heat recovery combined cycle, the thermal efficiency of the combined cycle unit without heat recovery is greatly improved. The new system of the combined cycle of the partial regenerative gas turbine has excellent performance under variable working conditions, and the design power of the system is almost equal to that of the combined cycle unit without regenerative, which has a good application prospect in engineering.

Description

A Novel Combined Cycle System of Partially Regenerating Gas Turbines

technical field

The invention belongs to the field of power station energy saving, and in particular relates to a novel combined cycle system of a partly regenerative gas turbine.

Background technique

The gas turbine combined cycle system is a high-efficiency cycle method that uses natural gas or oil as fuel to generate high-temperature and high-pressure flue gas through compressed air post-combustion, and then uses gas turbines and waste heat boilers to convert heat and power.

The gas turbine combined cycle system has the advantages of fast start-up, high thermal efficiency, strong peak-shaving capability, and low pollution. For the combined cycle of gas turbines, the initial combustion temperature continues to increase during the development of modern gas turbines, and the parameters of the steam turbine as a bottom cycle are also improving, and the efficiency of the combined cycle composed of them also increases. It has developed rapidly in recent decades. The heavy-duty gas turbines used in power stations have developed very rapidly in recent decades. The design pressure ratio and initial temperature have been continuously improved, and the efficiency and power output have been continuously increased. The series of products produced by GE Company are from 9E to The efficiency of the most advanced 9H-class gas turbine unit has increased from 33.89% to 41.8%, the efficiency of the combined cycle has increased from 52% to 61.8%, the output of the combined cycle has increased from 193.2MW to 755MW, the design pressure ratio has increased from 12.3 to 23, and the design flow And the temperature increased from 400kg/s and 1204°C to 685kg/s and 1436°C. With the improvement of the gas turbine cycle parameters, the main steam pressure of the waste heat boiler continues to increase. At present, the more advanced form of the waste heat boiler matched with the heavy-duty gas turbine is a triple-pressure reheat waste heat boiler.

Gas turbine combined cycle units are often operated under partial load conditions due to their participation in power grid peak regulation. As the gas turbine load decreases, its thermal efficiency decreases accordingly. Therefore, how to maintain a high thermal efficiency of gas turbine combined cycle under variable operating conditions is very important. important. The recuperation technology is used in the gas turbine combined cycle to improve its cycle efficiency, because it can obtain higher combustion chamber inlet temperature and less fuel consumption. Heating the fuel in the combined cycle can reduce the total fuel consumption under the same operating conditions of the gas turbine, where the bottom cycle feed water is a typical heat source for fuel heating. However, the arrangement of the regenerator will absorb the energy of the high-temperature section of the exhaust steam of the gas turbine, resulting in a serious decline in the power generation capacity of the combined cycle system.

Gas turbine combined cycle is a form of industrial power generation that has been vigorously developed in the world in recent decades. In order to adapt to the rapid development of the electricity market and the coordinated development between grid safety and clean environmental protection, we urgently need to find new ways to improve the efficiency of gas turbine combined cycle, which has become an increasingly important topic in my country's power generation industry.

The present invention proposes a new type of partial regenerative gas turbine combined cycle system, which is suitable for gas turbine combined cycle power plants. The load is adjusted by adjusting the proportion of the flue gas participating in the heat recovery, so that the thermal efficiency of the part of the heat recovery combined cycle is relatively higher than that of the combined cycle unit without heat recovery without losing more work of the combined cycle of the gas turbine. big boost. The new part-regeneration gas turbine combined cycle system has excellent performance under variable conditions, and the design power of the system is almost equal to that of the combined cycle unit without heat recovery, which has a good application prospect in engineering.

Contents of the invention

Aiming at the problems that the thermal efficiency of the gas turbine combined cycle is low under variable working conditions, and the power output of the simple regenerative cycle is much smaller than that of the non-regenerating cycle, the present invention proposes a new type of partial regenerative gas turbine combined cycle system belonging to the field of power station energy saving. Part but not all of the exhaust gas from the gas turbine is used for heat recovery, so that the thermal efficiency of the combined cycle can be greatly improved without losing more work of the combined cycle of the gas turbine.

To achieve the above object, the present invention adopts the following technical solutions:

A new type of partial regenerative gas turbine combined cycle system, the system mainly includes regenerator, gas turbine, combustion chamber, compressor, steam turbine high-pressure cylinder, steam turbine medium-pressure cylinder, steam turbine low-pressure cylinder, generator, condenser, high-pressure Superheater 2, reheater 2, reheater 1, high pressure superheater 1, high pressure evaporator, high pressure economizer 2, low pressure superheater, high pressure economizer 1, low pressure evaporator, low pressure economizer, water spray Desuperheater and other devices; its feature is that part of the exhaust gas from the gas turbine flows into the regenerator to preheat the outlet air of the compressor, and the reheated part of the exhaust gas is passed into the waste heat boiler before the reheater 1 of the bottom cycle, and the other part is exhausted The gas is directly passed into the high-pressure superheater 2 and reheater 2 of the waste heat boiler, and the exhaust gases from the two gas turbines are fully mixed before the reheater 1 and then flow through the reheater 1, high-pressure superheater 1, and high-pressure evaporator in sequence , High-pressure economizer 2, low-pressure superheater, high-pressure economizer 1, low-pressure evaporator, low-pressure economizer, and discharge to the atmosphere. After the water in the steam cycle comes out of the condenser, it flows into the low-pressure economizer and is divided into two streams, one flows through the high-pressure economizer 1, the high-pressure economizer 2, the high-pressure evaporator, the high-pressure superheater 1, and the high-pressure superheater After entering the high-pressure cylinder of the steam turbine to do work; the exhaust steam of the steam turbine flows through the reheater 1 and reheater 2 to reach a higher temperature after being reheated, and enters the medium-pressure cylinder of the steam turbine to continue to do work; the other fluid flows through the low-pressure evaporation The exhaust steam from the steam turbine and the low-pressure superheater is fully mixed with the exhaust steam from the medium-pressure cylinder of the steam turbine, and flows into the low-pressure cylinder of the steam turbine together to perform work; the exhaust steam from the low-pressure cylinder flows into the condenser and condenses into water. The compressor is coaxial with the gas turbine turbine and connected to the high-pressure cylinder of the steam turbine, the medium-pressure cylinder of the steam turbine, the low-pressure cylinder of the steam turbine, and the generator.

The system described is different from the simple regenerative gas turbine combined cycle. In this new cycle, part of the smoke exhaust from the gas turbine is used to reheat the air at the outlet of the compressor, not all of it is used for reheating; and in the design working condition, due to the The heat ratio is small, so the combined cycle output of the system is almost equal to the design output of the combined cycle without heat recovery cycle.

The temperature of the flue gas that has been reheated in the system is much lower than that of the flue gas that does not participate in the reheating, so the flue gas at the outlet of the regenerator is mixed with the flue gas at the outlet of the reheater 2 and then passed into the reheater 1, so as to make reasonable use of the flue gas air temperature distribution. The specific layout position of the reheated flue gas into the waste heat boiler is affected by the design structure of the waste heat boiler and the change of flue gas temperature distribution, so it can be adjusted according to different waste heat boiler structures to achieve the most reasonable application.

The system uses a new operation mode to adjust the load of the combined cycle, that is, to keep the turbine inlet temperature T3 constant at a higher load, and to reduce the load by adjusting the proportion of the flue gas participating in the reheating to the total flue gas, instead of Adjust the opening of the compressor IGV to reduce the air flow at the compressor inlet; at the same time, a bypass valve is designed on the outlet air of the compressor to flow into the regenerator pipe to adjust the air flow into the regenerator, so that the air flow occupies the air flow at the compressor inlet. The proportion of the air flow is equal to the proportion of the flue gas participating in the reheating to the total flue gas. This operation mode can maintain the thermal efficiency of the combined cycle close to the design condition when the combined cycle is under high load, which largely optimizes the problem of the sharp drop in efficiency of the gas turbine when the working condition changes, and has a good application prospect in engineering.

In the present invention, by arranging the regenerator in the combined cycle of the simple gas turbine, the exhaust heat of the gas turbine is fully utilized as a heat source to preheat the air at the outlet of the compressor, thereby increasing the temperature of the air at the inlet of the combustion chamber and reducing the amount of fuel required. Improve the thermal efficiency of the combined cycle; on this basis, transform the heat recovery cycle into partial heat recovery, that is, the exhaust smoke from the turbine is only used to preheat the air at the inlet of the combustion chamber, and the heat recovery ratio is small under the design working conditions. The combined cycle of the new system The power output is similar to that of the cycle without heat recovery, which effectively solves the problem of cycle power decline caused by heat recovery; the new system cooperates with the above-mentioned new adjustment method, which can keep the system relatively stable when the working conditions change. High thermal efficiency.

Description of drawings

Figure 1 is a schematic diagram of a new partial regenerative gas turbine combined cycle system

In the figure: 1-turbine; 2-combustion chamber; 3-regenerator; 4-compressor; 5-high pressure cylinder; 6-medium pressure cylinder; 7-low pressure cylinder; 8-generator; 9-high pressure superheater 2; 10-reheater 2; 11-reheater 1; 12-high pressure superheater 1; 13-high pressure evaporator; 14-high pressure economizer 2; 15-low pressure superheater; 16-high pressure economizer 1 ;17-low pressure evaporator; 18-low pressure economizer; 19-condenser; 20-spray desuperheater; 21-recirculation pump; 22-high pressure feed water pump; .

detailed description

The invention proposes a novel part-regeneration gas turbine combined cycle system. The following will be described in conjunction with the accompanying drawings and examples.

In the schematic diagram of the new partial regenerative gas turbine combined cycle system shown in Figure 1, the system mainly includes the regenerator, gas turbine, combustion chamber, compressor, steam turbine high pressure cylinder, steam turbine medium pressure cylinder, steam turbine low pressure cylinder, generator, Condenser, high pressure superheater 2, reheater 2, reheater 1, high pressure superheater 1, high pressure evaporator, high pressure economizer 2, low pressure superheater, high pressure economizer 1, low pressure evaporator, low pressure economizer Coal burner, spray desuperheater and other devices; characterized in that part of the exhaust gas from the gas turbine (1) flows into the regenerator (3) preheats the air at the outlet of the compressor (4), and the reheated part of the exhaust gas is circulated at the bottom The reheater 1 (11) of the waste heat boiler is passed into the waste heat boiler before, and the other part of the exhaust gas is directly passed into the high pressure superheater 2 (9) and reheater 2 (10) of the waste heat boiler. Heater 1 (11) is fully mixed before flowing through reheater 1 (11), high-pressure superheater 1 (12), high-pressure evaporator (13), high-pressure economizer 2 (14), low-pressure superheater (15 ), high-pressure economizer 1 (16), low-pressure evaporator (17), low-pressure economizer (18), and discharge to the atmosphere. After the water in the steam cycle comes out of the condenser (19), it flows into the low-pressure economizer (18) and is divided into two streams, one of which flows through the high-pressure economizer 1 (16) and the high-pressure economizer 2 (14) , high-pressure evaporator (13), high-pressure superheater 1 (12), high-pressure superheater 2 (9) and then enter the steam turbine high-pressure cylinder (5) to do work; steam turbine exhaust flows through reheater 1 (11), reheater 2 (10) After reheating, it reaches a higher temperature again, and enters the medium-pressure cylinder (6) of the steam turbine to continue to work; another fluid flows through the low-pressure evaporator (17), the low-pressure superheater (15), and then connects with the medium-pressure cylinder of the steam turbine. The exhaust steam from (6) is fully mixed and flows into the low-pressure cylinder (7) of the steam turbine together to do work; the exhaust steam from the low-pressure cylinder (7) flows into the condenser (19) and condenses into water. The gas compressor (4) is coaxial with the gas turbine turbine (1) and connected to the high pressure cylinder (5), the medium pressure cylinder (6), the low pressure cylinder (7) and the generator (8).

As shown in Figure 1, in the new partial regenerative gas turbine combined cycle system, part of the exhaust gas from the gas turbine (1) is used to reheat the outlet air of the compressor (4), rather than all used for reheating; and in the design In the working condition, because the proportion of heat recovery is small, the power output of the combined cycle of the system is almost equal to the design power of the combined cycle without the heat recovery cycle.

As shown in Figure 1, in the new partial regenerative gas turbine combined cycle system, since the temperature of the reheated flue gas is much lower than that of the flue gas that does not participate in the reheating, the flue gas at the outlet of the regenerator (3) and the reheater 2 (10) outlet flue gas is mixed and passed into reheater 1 (11), so as to make reasonable use of flue gas temperature distribution. The specific layout position of the reheated flue gas into the waste heat boiler is affected by the design structure of the waste heat boiler and the change of flue gas temperature distribution, so it can be adjusted according to different waste heat boiler structures to achieve the most reasonable application.

As shown in Figure 1, in a new type of partial regenerative gas turbine combined cycle system, a new operation mode is used to adjust the combined cycle load for the new system, that is, to keep the turbine (1) inlet temperature T3 constant at higher loads , to reduce the load by adjusting the proportion of the flue gas participating in the reheating to the total flue gas, instead of adjusting the opening of the compressor IGV to reduce the air flow at the inlet of the compressor (4); at the same time, the air at the outlet of the compressor (4) A bypass valve is designed on the pipe of the heater (3) to adjust the air flow into the regenerator (3), so that the proportion of the air flow to the air flow at the compressor inlet is equal to the proportion of the flue gas participating in the reheating to the total flue gas . This operation mode can maintain the thermal efficiency of the combined cycle close to the design condition when the combined cycle is under high load, which largely optimizes the problem of the sharp drop in efficiency of the gas turbine when the working condition changes, and has a good application prospect in engineering.

The present invention proposes for the first time that the exhaust part of the gas turbine is used to reheat the inlet air of the combustion chamber, and after improving the adverse effect of the low work output of the combined cycle caused by the regenerator, the position where the reheated flue gas enters the waste heat boiler is changed. Rational use of gas turbine smoke exhaust energy in stages, retaining high-temperature flue gas characteristics and thus maintaining steam cycle design parameters, using flue gas in a reasonable temperature range to improve gas turbine cycle performance, and finally achieving a significant improvement in the overall performance of the combined cycle without seriously affecting the output function force effect. At the same time, a new operation mode is used to adjust the load of the combined cycle for the new system, that is, the load is adjusted by adjusting the proportion of the flue gas participating in the heat recovery. The thermal efficiency of the cycle has largely optimized the problem of a sharp drop in the efficiency of the gas turbine when the working condition changes. Therefore, compared with the traditional regenerative cycle system, the partial regenerative gas turbine combined cycle system has a greatly improved engineering application prospect, and has strong practicality and scientific value.

Claims (4)

1. The present invention discloses a new type of partial recuperation gas turbine combined cycle system belonging to the field of power station energy saving. Low-pressure cylinder, generator, condenser, high-pressure superheater 2, reheater 2, reheater 1, high-pressure superheater 1, high-pressure evaporator, high-pressure economizer 2, low-pressure superheater, high-pressure economizer 1, Low-pressure evaporator, low-pressure economizer, water spray desuperheater and other devices; it is characterized in that part of the exhaust gas from the gas turbine (1) flows into the regenerator (3) to preheat the air at the outlet of the compressor (4), and after reheating Part of the exhaust gas is passed into the waste heat boiler before the reheater 1 (11) of the bottom cycle, and the other part of the exhaust gas is directly passed into the high-pressure superheater 2 (9) and reheater 2 (10) of the waste heat boiler. The turbine exhaust is fully mixed before the reheater 1 (11) and then flows through the reheater 1 (11), high-pressure superheater 1 (12), high-pressure evaporator (13), and high-pressure economizer 2 (14) , low-pressure superheater (15), high-pressure economizer 1 (16), low-pressure evaporator (17), low-pressure economizer (18), and discharge to the atmosphere; the water in the steam cycle comes out of the condenser (19) , flows into the low-pressure economizer (18), and is divided into two streams, one flows through the high-pressure economizer 1 (16), the high-pressure economizer 2 (14), the high-pressure evaporator (13), and the high-pressure superheater 1 (12 ), the high-pressure superheater 2 (9) enters the high-pressure cylinder (5) of the steam turbine to do work; the exhaust steam of the steam turbine flows through the reheater 1 (11) and the reheater 2 (10) to reach a higher temperature after reheating, and Enter the medium-pressure cylinder (6) of the steam turbine to continue to work; another fluid flows through the low-pressure evaporator (17) and the low-pressure superheater (15), and then fully mixes with the exhaust steam from the medium-pressure cylinder (6) of the steam turbine, and flows into the low-pressure steam turbine together. Cylinder (7) works; the exhaust steam of low-pressure cylinder (7) flows into condenser (19) and condenses into water; compressor (4) is coaxial with gas turbine turbine (1) and connected to high-pressure cylinder (5) of steam turbine, steam turbine Medium pressure cylinder (6), steam turbine low pressure cylinder (7), generator (8). 2. A novel partial regenerative gas turbine combined cycle system according to claim 1, characterized in that: different from the simple regenerative gas turbine combined cycle, the smoke exhaust part of the gas turbine (1) in the new cycle is used for recycling The outlet air of the hot compressor (4) is not all used for heat recovery; and in the design working condition, because the proportion of heat recovery is small, the combined cycle output of the system and the combined cycle design without heat recovery cycle nearly equal. 3. A new type of partly regenerative gas turbine combined cycle system according to claim 1, characterized in that: since the temperature of the reheated flue gas is much lower than that of the flue gas that does not participate in the reheating, the regenerator (3) The flue gas at the outlet is mixed with the flue gas at the outlet of the reheater 2 (10) and then passed into the reheater 1 (11), so that the temperature distribution of the flue gas can be used reasonably; The design structure and flue gas temperature distribution change, so it can be adjusted according to different waste heat boiler structures to achieve the most reasonable application. 4. A new type of partial regenerative gas turbine combined cycle system according to claim 1, characterized in that: for the new system, a new operation mode is used to adjust the combined cycle load, that is, to keep the turbine ( 1) The inlet temperature T3 remains unchanged, and the load is reduced by adjusting the proportion of the flue gas participating in the reheating to the total flue gas, instead of adjusting the opening of the compressor IGV to reduce the air flow at the inlet of the compressor (4); at the same time, the compressor ( 4) A bypass valve is designed on the outlet air flow into the regenerator (3) to adjust the air flow into the regenerator (3), so that the ratio of the air flow to the inlet air flow of the compressor and the flue gas participating in the reheating The proportion of the total flue gas is equal; this operation mode can maintain the thermal efficiency of the combined cycle close to the design working condition under the high load of the combined cycle, which largely optimizes the problem of the sharp drop in the efficiency of the gas turbine when the working condition changes. There are good application prospects.